One of my favorite books is "The Lucifer Effect" by Philip Zimbardo, who ran the Stanford Prison Experiment and was called in as an expert witness in a 2004 court martial on Abu Ghraib. By his logic, it's not hard to argue that higher-ups share complicity for some of the abuses that occur, for the simple fact that they establish and administer a social and procedural environment that condones, permits, or overlooks prisoner abuse instances as well as the behavior that leads up to them.